<?php

$user["60"] = array("id" => "60", "num" => "56", "count" => "31");
$user["61"] = array("id" => "61", "num" => "22", "count" => "34");
$user["59"] = array("id" => "59", "num" => "32", "count" => "43");
$user["56"] = array("id" => "56", "num" => "41", "count" => "38");
$user["57"] = array("id" => "57", "num" => "39", "count" => "65");

$keys = array_keys($user); //返回包含数组中所有键名的一个新数组

var_dump($keys);